Season of birth and parental age in right, mixed and left handers

Karev, George B.

doi:10.1016/j.cortex.2006.01.001

Cited by 16 publications

(9 citation statements)

References 8 publications

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“…In other studies, more left-handers were found among children born in March-July (29,30,51), but in other studies in winter (49,50,52). In yet other studies, no effect of season was detected (31,(53)(54)(55). In the UK biobank, we observed that birthweight varied with season, with a pattern that was similar in males and females: the highest average birthweight was in September-October and lowest in February ( Figure S6 ) (56).…”

Section: Environmental Effectssupporting

confidence: 42%

“…In addition to the factors investigated in this study, other early life factors have been reported in the literature, including birth order (Badian, 1983;Bakan, 1971Bakan, , 1977Hicks et al, 1978), prenatal testosterone exposure (Elkadi et al, 1999;Lust et al, 2011;Vuoksimaa et al, 2010), maternal age (Badian, 1983;Coren and Porac, 1980;Karev, 2008;McKeever et al, 1995), maternal stress during pregnancy (Reissland et al, 2015;Searleman et al, 1989), and birth events such as caesarean delivery or prolonged labour (Bailey and McKeever, 2004;Nicholls et al, 2012;Van der Elst et al, 2011). Though not all studies have found significant effects of these variables, a general interpretation of the literature is that less benign conditions are associated with higher proportions of left-handedness.…”

Section: Additional Early Life Factorsmentioning

confidence: 84%

“…In addition to the factors investigated in this study, other early life factors have been reported in the literature, including birth order (49,(60)(61)(62), prenatal testosterone exposure (63-65), maternal age (49,53,66,67), maternal stress during pregnancy (11,68), and birth events such as caesarean delivery or prolonged labour (12,57,69). Though not all studies have found significant effects of these variables, a general interpretation of the literature is that less benign conditions are associated with higher proportions of left-handedness.…”

Section: Additional Early Life Factorsmentioning

confidence: 99%

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A large-scale population study of early life factors influencing left-handedness

Kovel

Carrión-Castillo

Francks

2018

Preprint

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Running Title: Handedness and early life factors in the UK Biobank AbstractHand preference is a conspicuous variation in human behaviour, with a worldwide proportion of around 90% of people preferring to use the right hand for many tasks, and 10% the left hand. As the developmental foundations of hand preference occur in utero, with further establishment within the first two years of life, prenatal and early-life factors are likely to play a role. Various, often related, factors have been studied in the past, but often in small samples, or samples with biased selection schemes. We used the large, general population cohort of the UK biobank (~500,000 participants) to study possible relations between early life factors and adult hand preference. The probability of being left-handed was affected by the year and location of birth, birthweight, being part of a multiple birth, season of birth, breastfeeding, as well as sex, with each effect remaining significant after accounting for all others. Maternal smoking showed no association with handedness. Analysis of genome-wide polymorphism data indicated a tentative genetic correlation between handedness and birth-weight, which was opposite to their overall phenotypic correlation. However, the total effect on handedness of all these factors was very small. Therefore other, unknown effects must be involved, including possible environmental factors, and/or random developmental variation with respect to the left-right formation of the embryonic brain.

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Section: Environmental Effectssupporting

confidence: 42%

Section: Additional Early Life Factorsmentioning

confidence: 84%

Section: Additional Early Life Factorsmentioning

confidence: 99%

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A large-scale population study of early life factors influencing left-handedness

Kovel

Carrión-Castillo

Francks

2018

Preprint

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“…In other studies, more left-handers were found among children born in March-July 28,29,51 , but in other studies in winter 49,50,52 . In yet other studies, no effect of season was detected 30,53–55 . A meta-analysis published in 2008, based on data from more than 40,000 participants, found primarily that left-handed men had a slight tendency to have been born from March–July (in the northern hemisphere) 51 .…”

Section: Discussionmentioning

confidence: 70%

A large-scale population study of early life factors influencing left-handedness

Kovel

Carrión-Castillo

Francks

2019

Sci Rep

131

146

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Hand preference is a conspicuous variation in human behaviour, with a worldwide proportion of around 90% of people preferring to use the right hand for many tasks, and 10% the left hand. We used the large cohort of the UK biobank (~500,000 participants) to study possible relations between early life factors and adult hand preference. The probability of being left-handed was affected by the year and location of birth, likely due to cultural effects. In addition, hand preference was affected by birthweight, being part of a multiple birth, season of birth, breastfeeding, and sex, with each effect remaining significant after accounting for all others. Analysis of genome-wide genotype data showed that left-handedness was very weakly heritable, but shared no genetic basis with birthweight. Although on average left-handers and right-handers differed for a number of early life factors, all together these factors had only a minimal predictive value for individual hand preference.

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“…Although not confirmed by other studies (85,114,159), independent reports in humans found significantly more LHs among the males born in winter (152,160). One hypothesis is that GE49CH26-Roussigne ARI 27 September 2015 14:54 seasonal variation in the mother's hormones, such as high levels of androgens during spring, could influence fetal development and contribute, together with genetic factors, to induce a left shift.…”

Section: Hormonesmentioning

confidence: 86%

Asymmetry of the Brain: Development and Implications

et al. 2015

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Although the left and right hemispheres of our brains develop with a high degree of symmetry at both the anatomical and functional levels, it has become clear that subtle structural differences exist between the two sides and that each is dominant in processing specific cognitive tasks. As the result of evolutionary conservation or convergence, lateralization of the brain is found in both vertebrates and invertebrates, suggesting that it provides significant fitness for animal life. This widespread feature of hemispheric specialization has allowed the emergence of model systems to study its development and, in some cases, to link anatomical asymmetries to brain function and behavior. Here, we present some of what is known about brain asymmetry in humans and model organisms as well as what is known about the impact of environmental and genetic factors on brain asymmetry development. We specifically highlight the progress made in understanding the development of epithalamic asymmetries in zebrafish and how this model provides an exciting opportunity to address brain asymmetry at different levels of complexity.

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Season of birth and parental age in right, mixed and left handers

Cited by 16 publications

References 8 publications

A large-scale population study of early life factors influencing left-handedness

A large-scale population study of early life factors influencing left-handedness

A large-scale population study of early life factors influencing left-handedness

Asymmetry of the Brain: Development and Implications

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